The rise of additive manufacturing (AM) has enabled the rapid production of complex part geometries across multiple material domains. To date, however, AM of inorganic semiconductor materials has not been fully realized due to the difficulty of forming single-crystal materials with traditional AM processes. Here, we demonstrate a novel semiconductor synthesis method using a combination of liquid and gas precursors to additively print gallium nitride. Growth rates of 1–2 µm/min are demonstrated in printed regions while maintaining epitaxial alignment with the substrate. We also outline critical variables for the future development, improvement, and implementation of the proposed process.

This work is based on a recent theoretical study of how the hydrostatic pressure and core/shell sizes affect the optical properties associated with the transition from the ground state to first excited state (1s–1p), of an exciton confined in spherical core/shell quantum dots (SCSQDs). We have computed under an effective mass framework, linear, third-order nonlinear, and total absorption coefficients (AC) and refractive index (RI) as functions of photon energy for different sizes of SCSQDs with varying hydrostatic pressure. Our results show that the optical absorption is deeply dependent on the incident light intensity. Both AC and RI significantly influenced by the confinement and pressure effects.

Three-dimensional (3D) printed poly (ethylene glycol) diacrylate (PEGDA) objects have been reinforced with 1%, 3% and 5% silica (SiO2) nanoparticles. Rheological characterizations were conducted for each formulation and 3D-printed using a stereolithographic apparatus (SLA) 3D printer. The tensile and compressive properties of the as-printed nanocomposites were investigated and compared with unreinforced samples. Additionally, the mechanical properties of the objects before and after swelling the samples in deionized water were compared with as-printed ones. Adding SiO2 increased the tensile and compressive strengths of the 3D-printed PEGDA. The tensile and compressive strengths of swollen PEGDA/SiO2 nanocomposite specimens were generally higher than the unswollen specimens.

A glucose-reduced, room temperature-synthesized colloidal Cu2O solution (CCS) was used for the first time to detect humic acid (HA), a carcinogen-promoting substance in aqueous solution. The CCS sensor was characterized using standard spectroscopy and microscopy techniques. The sensor evolved as a carboxylic acid-capped peach-pink solution after synthesis. The result of the interaction of the sensor with HA in phosphate buffer solution (pH 7) showed a detection limit of 1.5891 × 10−2 mg/L over a concentration range of 0.00–0.41 mg/L. This finding suggests that the sensor may be useful for monitoring low levels of HA in aqueous environments.

Poly(3,4-ethylenedioxythiophene) (PEDOT) is synthesized through a micellar dispersion that allows incorporation of biomolecules into this conductive polymer layer. A PEDOT:κ-carrageenan (κC) system was obtained by electrodeposition and it was compared with a standard PEDOT:sodium dodecyl sulfate electrode coat. The electrochemical behavior and the oxidation level after 1000 cycles were studied through cyclic voltammetry and μRaman spectroscopy. The oxidation ratio in the PEDOT increased while electrochemical activity decreased in both cases. Moreover, the PEDOT:κC system allowed the immobilization of the acetylcholinesterase enzyme, which retained its activity. The unique combination of properties is a key feature in the bioelectronics field.

Development of biomaterials with primary amine surfaces is very important for the study of some cells of the immune systemuch as macrophages. Currently, the modification can be carried out by physical or chemical methods with several disadvantages due to the presence of additives or subproducts in the system. To overcome this problem, modified polypropylene (PP) films were synthesized by gamma radiation. In this work, radiation grafting of acryloyl chloride onto PP has been employed to form an acyl chloride. Then, the radiation-grafted films were reacted with ethylenediamine in several solvents to obtain the different concentration of the primary amine. The surface amine concentration was determined by derivatization with 4-trifluoromethyl benzaldehyde and characterized by x-ray photoelectron spectroscopy (N/C ratios), Fourier transform infrared spectroscopy with attenuated total reflection, contact angle, scanning electron microscopy, atomic force microscopy, and elementary analysis. The stability of the amines was measured up to 90 days, without the occurrence of aging as was found by plasma modification.

In the past decades, efforts have been made to couple nanoindentation with resistive measurements in order to monitor the real-time contact area, as an alternative to the use of traditional analytical models. In this work, a novel and efficient stand-alone method is proposed to compute the contact area using resistive-nanoindentation of noble metals (bulk or thin films). This method relies on three steps: tip shape measurement, set-up calibration, application to the sample to be characterized. The procedure is applied to nanoindentation tests on a sample with film-on-elastic-substrate rheology and is successfully validated against experimental measurements of the contact area.

We have successfully employed a charge transfer mechanism to convert carbon nanotube (CNT) powder into CNT flexible membrane with no binder. We have demonstrated the use of the CNT membranes as electrode in a stacked bipolar solid-state capacitor using grafoil as current collector that showed 80% capacitance retention over 10,000 cycles at 70 °C. The CNT membranes could have potential application in catalysis, photovoltaic, thermoelectric, and many others.

To examine the influence of ultrasonic irradiation on electrochemical migration (ECM), the morphology of micro/nanodeposits and current change were studied. The morphology of deposits synthesized by ECM varied with the types of ultrasonic irradiation: continuous or pulsed irradiation generates only particles or deposits composed of wires, dendrites, and particles. The measured ECM current change over time concludes that both mechanical and sonochemical effects contributed to the morphological change of deposits. Shock waves by cavitation mechanically formed the fragmented deposits and the sonochemical effect decreases the ionic concentration corresponding to decreasing current, inhibiting the formation of wires and dendritic deposits.

Polymeric electrolytes have attracted recent research interest because they offer the advantages of being safe and non-flammable, having no dendrite formation, and having no possibility of leakage. The incorporation of synthetic polymers to gel electrolytes has numerous disadvantages: for instance, the required preparation time for creating gel electrolytes from synthetic polymers is dubious and lengthy. Additionally, the conventional pristine polymer gel electrolyte layer has been reported to have low ionic conductivity. This work is focused on preparing a thin flexible gel electrolyte layer by using a naturally occurring wood-based nanofiber cellulose (NFC) hydrogel, to overcome the energy and time consumption of conventional processes. In addition, we use polyvinyl alcohol (PVA) as an additive to the NFC hydrogel in controlled amounts to fabricate a stable thin gel electrolyte layer. By using x-ray diffraction, optical microscopy, and Fourier transform infrared spectra studies, we were able to further our understanding of the microstructure of the films: i.e., the penetration and cross-linking (changes in the bonding structures) of semi-crystalline PVA and hydrogel to form a flexible gel electrolyte layer. The NFC hydrogel-PVA films resulted in much higher ionic conductivity values when compared to other existing pristine polymer electrolytes. The addition of KOH to the NFC hydrogel-PVA further enhanced the ionic conductivity. The best ionic conductivity recorded was 75 mS/cm for films with thickness in the range of 200–350 µm, which is comparable to the highest reported ionic conductivity values of gel electrolytes.

Resonant soft x-ray scattering (RSoXS) leverages chemical specificity to characterize thin films but is limited near the nitrogen edge. The challenge is that commercially available x-ray transparent substrates are composed of Si3N4 and thereby absorb incident x-rays and generate incoherent fluorescence. To overcome this challenge, we designed and fabricated Al2O3 free-standing films for use as RSoXS windows. Al2O3 films offer higher x-ray transmittance and minimal fluorescence near the nitrogen edge. As an example, Al2O3 windows allow for nitrogen RSoXS of conjugated block copolymer thin films that reveal domain spacings, which are not apparent with commercially available Si3N4 substrates.

One of the critical components of energy savings in buildings is thermal insulation, especially for windows in cold climates. The conventional approach mainly relies on a double-pane design. In this study, a new concept of “Green Window” has been designed for single-pane applications that lower the U-factor. The “Green Window” is structurally and simply composed of a thin film window coating of chlorophyll that exhibits pronounced photothermal effect, while remaining highly transparent. We demonstrate a new concept in “thermal insulation” via optical means instead of solely through thermal insulators or spectral selectivity. This concept lifts the dependence on insulating materials making single-pane window highly possible.

Methods for the control of molecular deposition and orientation are critical for the development of organic electronic devices. Here, we show the fabrication of ribbons of the optical material polydiacetylene (PDA) using a controlled evaporative self-assembly method. The ability to form these ribbons is highly dependent on both the side groups on the PDA as well as the solvent used in the preparation. Arrays of ribbons of one type of PDA, poly[1,6-di(N-carbazolyl)-2,4-hexadiyne], with widths on the order of 1–2 µm and lengths of 100s of micrometers, could be successfully obtained with good orientation.

Powering autonomous electronic devices is a key challenge toward the development of smart sensor networks. In this work, a state-of-the-art triboelectric nanogenerator is devised to enhance the output performance with an effective surface charge density of 70.2 µC/m2, which is 140 times higher than the initial results. Thin film Parylene-C material is deposited to increase charge accumulation by allowing the acceptance of more charges and enhance output performance by a factor of 10. By considering the merit of simple fabrication, we believe the effective charge inclusion layer will be an ideal energy source for low-power portable electronics.

Powerful synergies between phosphonate, zinc oxide, and acrylamido-tert-butyl-sulfonate (ATBS) copolymer chemical additives render superior performance in a high-temperature retarder system for oil well grade Portland cement. The phosphonate retarder and ATBS-based retarders establish a two-tiered strength development where amorphous C-S-H converts to crystalline dicalcium silicate hydrate (C2SH) in the first (low compressive strength) tier prior to the reaction of Portlandite with quartz. The three additive retarder system can be tuned with nanosilica to eliminate the two-tiered strength development effect leading to a smooth transition from the cement in the slurry form directly to its highest compressive strength.

A low-cost synthesis approach was developed for the fabrication of four symmetric meso-substituted water-soluble thiolated polyethylene glycol gold-coated superparamagnetic iron oxide nanoparticles–porphyrin (p-hydroxyphenyl [THPP], 3,5-dimethoxyphenyl [TdMPP], 3-pyridyl[T-3-PyP], and 1-methylpyridinium-3-yl[T3-Py+P4I−]) conjugates to achieve materials with enhanced absorption and therapeutic properties. After evaluation of their antibacterial inhibition characteristics against four nocosomial pathogens (Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis), THPP and TdMPP conjugates showed some remarkable minimum inhibitory concentration values of 0.104 and 0.625 mg/mL against E. coli and E. faecalis, respectively, making these materials to be alternative agents for the inhibition of these pathogens in the environmental and clinical fields.

A facile and low-cost method based for tension gradient self-assembly was developed to prepare polytetrafluoroethylene (PTFE) nanofiber coatings on stainless-steel fiber felts. The PTFE particles were used as building blocks and the self-assembly process was analyzed thoroughly. After being sintered, the PTFE particles were transformed into PTFE nanofibers. The felts coated with the PTFE nanofibers exhibited superhydrophobicity and superoleophilicity, and could separate a series of oil–water mixtures with high efficiency and good reusability. The coated felts also presented excellent chemical and thermal stabilities. Over all, this approach could easily fabricate ultra-robust oil–water separation materials suitable for industrial applications.

The strength of single-crystalline nanoscale metals is controlled by dislocation nucleation from free surfaces. Surface properties such as crystallographic orientation, surface stress, and surface diffusion have been proposed as key parameters that control dislocation surface nucleation, but have not been confirmed experimentally. To investigate the influence of surface parameters, in situ scanning electron microscope mechanical testing is used to compress defect-free Ag and Cu nanocubes that are passivated with organic surfactants in order to tune their surface properties. Comparison between passivated nanocubes indicates that yield strength may depend on surfactant binding energy, but is also dependent on intrinsic material properties.

Polymer electrolyte membrane fuel cells (PEMFCs) provide a renewable source of energy through the redox reaction of hydrogen and oxygen gas; however, operation relies on a costly platinum catalyst layer. This study investigates how electrospun catalyst layers may be employed to increase the surface area:volume ratio for catalysis to optimize PEMFC performance. When preparing electrospinning solutions, several base polymers were evaluated in varying concentrations to optimize fiber formation, with poly(acrylic acid) found to be preferable at a 12 wt% concentration. Ultimately, PEMFCs with electrospun catalyst layers achieved a 108% increase in power output compared to those air-sprayed.

To systematically investigate the influence of electrolyte substrates on Sr-segregation and SrSO4 formation in (LaSr)(CoFe)O3 (LSCF) cathodes in solid oxide fuel cells, model thin films were grown on Gd-doped ceria (GDC) and on Y-doped BaZrO3 (BZY) electrolytes by pulsed laser deposition and heat treated at 800–1000 °C in synthetic air with a trace amount of SO2. A severe SrSO4 formation was observed in LSCF on GDC as compared with the BZY, especially at low temperature. The difference in Sr-segregation and SrSO4 formation on the LSCF was discussed in relation to Sr diffusion and related elemental redistribution across the interfaces.